

using System;
using System.Security.Cryptography;
using System.Text;

namespace BDFramework.Hash
{
    public class HashHelper
    {
        public static string CreateMD5ByString(string input)
        {
            // Use input string to calculate MD5 hash
            MD5 md5 = System.Security.Cryptography.MD5.Create();
            byte[] inputBytes = System.Text.Encoding.ASCII.GetBytes(input);
            byte[] hashBytes = md5.ComputeHash(inputBytes);

            // Convert the byte array to hexadecimal string
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < hashBytes.Length; i++)
            {
                sb.Append(hashBytes[i].ToString("x2"));
            }

            return sb.ToString();
        }

        /// <summary>
        ///  计算指定文件的MD5值
        /// </summary>
        /// <param name="fileName">指定文件的完全限定名称</param>
        /// <returns>返回值的字符串形式</returns>
        public static string CreateMD5ByFile(String fileName)
        {
            string hashMD5 = String.Empty;
            //检查文件是否存在，如果文件存在则进行计算，否则返回空值
            if (System.IO.File.Exists(fileName))
            {
                using (System.IO.FileStream fs = new System.IO.FileStream(fileName, System.IO.FileMode.Open, System.IO.FileAccess.Read))
                {
                    //计算文件的MD5值
                    System.Security.Cryptography.MD5 calculator = System.Security.Cryptography.MD5.Create();
                    Byte[] buffer = calculator.ComputeHash(fs);
                    calculator.Clear();
                    //将字节数组转换成十六进制的字符串形式
                    StringBuilder stringBuilder = new StringBuilder();
                    for (int i = 0; i < buffer.Length; i++)
                    {
                        stringBuilder.Append(buffer[i].ToString("x2"));
                    }

                    hashMD5 = stringBuilder.ToString();
                } //关闭文件流
            } //结束计算

            return hashMD5;
        }
    }
}

